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Publications of the Week

Viral Proteins as a Potential Driver of Histone Depletion in Dinoflagellates

By May 4, 2018No Comments

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 This week we profile a recent publication in Nature Communications from Dr. LeAnn Howe (far left)
and Nicholas Irwin (second from left) at the UBC Life Sciences Institute.

Can you provide a brief overview of your lab’s current research focus?

Multicellular  organisms  are  comprised  of  different  cell  types  that  share  the  same  genome.  Cell  identity  is  therefore  defined  by  the  unique  collection  of  genes that  are  transcribed  in  each  cell  type.    Factors  that  regulate  gene  expression  can  be  roughly divided  into  two  classes:  those  that  bind  to  and  maintain  genes  in  an  “ON”  state  and  those that  bind  to  and  maintain  genes  in  an  “OFF”  state.    One class of proteins that appear to perform both functions are histones, well conserved proteins that package DNA in all eukaryotes.  By studying organisms with atypical histones, we are learning about the critical roles these proteins play in maintaining gene expression states.

What is the significance of the findings in this publication?

The packaging of DNA with histones is a hallmark of eukaryotic chromosomes.  One surprising exception is dinoflagellates, a group of unicellular eukaryotic algae, which have abandoned histones as the primary DNA packaging protein and instead employ a viral-derived proteins termed dinoflagellate-viral-nucleoproteins (DVNPs).  In this study, we sought to understand the molecular events that facilitated histone replacement by DVNP in the dinoflagellate ancestral organism.  Using budding yeast, were able to recapitulate histone loss due to DVNP expression, suggesting that development of the unique chromatin structure of dinoflagellates may have been triggered by viral stress.

What are the next steps for this research?

While histones proteins have been difficult to detect in dinoflagellates, the histone genes are still present, suggest that at least some of the genome retains canonical chromatin packing.  We are currently investigating whether these genes are expressed and where the resulting histone proteins may be found.

This research was funded by:

The lab is supported by and NSERC Discovery Grant and Nick is supported by an NSERC Graduate Student Fellowship.

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